Simulate funding an internal account

Simulate receiving funds into an internal account in the sandbox environment. This is useful for testing scenarios where you need to add funds to a customer’s or platform’s internal account without going through a real bank transfer or following payment instructions. This endpoint is only for the sandbox environment and will fail for production platforms/keys.

POST /sandbox/internal-accounts/{accountId}/fund

cURL

cURL

curl --request POST \
  --url https://api.lightspark.com/grid/2025-10-13/sandbox/internal-accounts/{accountId}/fund \
  --header 'Authorization: Basic <encoded-value>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "amount": 100000
}
'

200

{
  "id": "InternalAccount:12dcbd6-dced-4ec4-b756-3c3a9ea3d123",
  "type": "INTERNAL_FIAT",
  "balance": {
    "amount": 12550,
    "currency": {
      "code": "USD",
      "name": "United States Dollar",
      "symbol": "$",
      "decimals": 2
    }
  },
  "fundingPaymentInstructions": [
    {
      "accountOrWalletInfo": {
        "accountType": "USD_ACCOUNT",
        "accountNumber": "1234567890",
        "routingNumber": "021000021"
      },
      "instructionsNotes": "Please ensure the reference code is included in the payment memo/description field",
      "isPlatformAccount": true
    }
  ],
  "createdAt": "2025-10-03T12:30:00Z",
  "updatedAt": "2025-10-03T12:30:00Z",
  "customerId": "Customer:019542f5-b3e7-1d02-0000-000000000001"
}

Authorizations

Authorization · string · header · required

API token authentication using format <api token id>:<api client secret>

Path Parameters

accountId · string · required

The ID of the internal account to fund

Body

application/json

amount · integer<int64> · required

Amount to add in the smallest unit of the account's currency (e.g., cents for USD/EUR, satoshis for BTC)

Required range: x <= 100000000000

Example:

100000

Response

200

application/json

Internal account funded successfully

id · string · required

The ID of the internal account

Example:

"InternalAccount:12dcbd6-dced-4ec4-b756-3c3a9ea3d123"

type · enum<string> · required

Classification of an internal account.

• INTERNAL_FIAT: A Grid-managed fiat holding account (for example, the USD holding account used as the source for Payouts flows).
• INTERNAL_CRYPTO: A Grid-managed crypto holding account denominated in a stablecoin such as USDC.
• EMBEDDED_WALLET: A self-custodial Embedded Wallet provisioned for the customer. Outbound transfers require a session signature produced by the customer's device — see the Embedded Wallets guide.

Available options: INTERNAL_FIAT, INTERNAL_CRYPTO, EMBEDDED_WALLET

balance · object · required

Show child attributes

fundingPaymentInstructions · object[] · required

Payment instructions for funding the account

Show child attributes

createdAt · string<date-time> · required

Timestamp when the internal account was created

Example:

"2025-10-03T12:30:00Z"

updatedAt · string<date-time> · required

Timestamp when the internal account was last updated

Example:

"2025-10-03T12:30:00Z"

customerId · string

The ID of the customer associated with the internal account. If this field is empty, the internal account belongs to the platform.

Example:

"Customer:019542f5-b3e7-1d02-0000-000000000001"